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charge question

italian_guy007us01 on Fri May 23, 2008 3:59 PM User is offline

Year: 1995
Make: chevy
Model: tahoe
Engine Size: 350
Refrigerant Type: r134

OK
since I couldnt find the capacity of 134 for my car, I decided to charge based on the AC lines itself feeling for any notable line temp differences. I charged the first can via liquid through high side port. The second can went in as gas through low side port as I kept the can in hot water to speed the charge. When I tried the third can, it really didn't take the charge for whatever reason; I was shooting for a total of maybe 1/2 can on the 3rd can but the car took none of the third. However, the compressor seems to be cycling and the vent temps feel like they are mid 50's although I havent checked yet. The accumulator is very cold and the line leading into it feels kinda damp. Did I do anything wrong or should I leave well enough alone? Thanks in advance

Ben

mk378 on Fri May 23, 2008 4:11 PM User is offline

From the NAPA capacity book (link in the Procedures Tips and FAQs forum here).

Tahoe 99-94 front air only: 36 oz R-134a. Three full cans.

Edit: You did evacuate first, right?

Edited: Fri May 23, 2008 at 4:13 PM by mk378

italian_guy007us01 on Fri May 23, 2008 4:14 PM User is offline

Yep
pulled a deep vacuum 30in Hg for well over 2 hrs and it held the vacuum without any leaks
Then I recharged....I'm stumped as to why it wont take 3rd can yet the vent temps feel cool.....

mk378 on Fri May 23, 2008 4:22 PM User is offline

It'll take that can eventually. Charging as gas can take a while. Just keep an eye on the high side pressure in case the book is wrong.

italian_guy007us01 on Sat May 24, 2008 9:50 AM User is offline

Ok
I hooked up the guages and tried to get that third can to go in. Well, I managed to get 3/4 of that can to go in. Vent temps feel very cold. After a test drive, I popped the hood and I saw that the line going into the accumulator as well as the whole accumulator itself was "sweating" Is this normal? What causes the "sweating" if abnormal?

Thanks

Chick on Sat May 24, 2008 9:19 PM User is offlineView users profile

Sweating means it's it's working, pulling the moisture out of the air... thats why you usually see a lot of water dripping on a humid day under the evaporator...I would try to get the rest of the charge in though..What are your pressures?? no reason the whole can wouldn't go in unless the low suide was to high..

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Chick
Email: Chick

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Freedoms just another word for nothing left to lose

italian_guy007us01 on Sat May 24, 2008 10:13 PM User is offline

Chick
as a matter of fact, you are correct, the low pressure was shooting waaay up. I thought that my eyes were deceiving me. With the car running, I was getting 80? but when I dipped the can in hot water, the low side press shot way up to 120...at this time, I cut off the can valve and closed the low side valve. The high side was shooting to 130ish and it was a cool NJ 60 degrees out.....I know, something doesnt make sense here. i have some AC experience and I should see low(suction side around 30-40 and a high of 2-2.25 times ambient temp. When I saw that 120 on the high side, I stopped because I felt a lil uneasy with that pressure......
With the vent temps prob in low to mid 40's and the sweating accumulator....I figure I will quit now before I make a critical mistake....further suggestions are appreciated!!

italian_guy007us01 on Sat May 24, 2008 10:17 PM User is offline

OOPS
I meant 120 on the low side...NOT high side..that is why I quit..didn't want anything exploding on me ..heck the low side gague was all the way to the right and THAT made me VERY uneasy....LOL

iceman2555 on Sun May 25, 2008 12:48 AM User is offlineView users profile

The low side pressure was high....because you are reading the pressure in the can...not the system.....shut the low side valve and the pressures should drop down to a more acceptable (?) reading.
Hopefully the can was in WARM water...not hot.....hot can be dangerous.....
Keep at it....it will take the remainder of the refrigerant...then once the temp gets above 75-77 degrees.....recheck the system....actually need a bit more ambient heat to make the system truly work.
Also keep in mind that the system will require more than the three cans ....the hose/manifold assm will need to be precharged to accommodate their volume.....unless one uses a specific method to disconnect charging hoses and recover the contained refrigerant. Standard hose/manifold will need app 4.5 oz to precharge. This short fall is sufficient to result in possible compressor damage due to lack refrigerant to insure complete lubricate migration.

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